Process and apparatus for refrigeration



1949. R. K. DEUTSCH ETAL 2,479,82i

PROCESS AND APPARATUS FOR REFRIGERATION Filed March 30, 1946 2Sheets-Sheet 1 lnven1'orsi Reba-1' K. DeuTSch Frflfh-iof A. LarsonVernon E. Middlebrook s fhdr MTofnuy AL ,1949. R. K. DEUTSCH ETAL2,479,821

PROCESS AND APPARATUS FOR REFRIGERATION Filed March 30, 1946 2Sheets-Sheet 2 Then-nos 1 Fiqly \nventolbi Rcgbefl K. DeuTsch FrrkhJofA. Larson Vernon E. Middiebrook Patented Aug. 23, 1949 PROCESS ANDAPPARATUS FOR REFRIGERATION Robert K. Deutsch, Chicago, Ill., Frithjoi'A. Larson, Bronxville, N. Y., and VernonE. Middlehrook, TulsayOkla,assignors to Shell Development Company, San Francisco, Calif., acorporation of Delaware Application March 30, 1946, Serial No. 658,492

9 Claims. (Cl. .62-2) This invention relates to the cooling or refrieration of food stuffs and is particularly concerned with the safe andeconomical preservation of food stuffs during transportation from placeto place, for example by various transport means such as railroad cars,motor trucks and cargo vessels.

The invention is primarily concerned with keeping fresh food stufls at asufllciently low temperature during transportation so that deteriorationof the food stuffs is prevented.

As is well known, it is an usual procedure to transport fresh foodstuffs both from production area to distribution areas and from primarydistribution areas to secondary distribution areas or to consumers inrefrigerated compartments. In the case of railroad shipment, speciallybuilt refrigerator cars are used for this purpose. These usuallycomprise a well insulated. closed compartment similar in appearance tothe usual box car, but having ice bunkers generally at each end forcarrying of about five tons of ice and salt. The ice and salt being inclose proximity to the contents of the storage section of therefrigeration car serve to keep the contents within the desiredtemperature range, principally by air convection.

The ice bunkers are provided with hatches in the roof of therefrigerator cars so that the ice may be replenished when necessary inorder that the food stuffs being transported do not spoil due to the icehaving melted.

Similarly refrigerated motor trucks are used to transport smallquantities of food stuffs from place to place by highways. While the useof ice as a refrigerant in the manner above outlined has the advantageof simplicity, yet it has many disadvantages such as requiring frequentreicing during long journeys (or when stoppages in trafiic occur), thecarrying of a large dead load with its attendant loss in usable spacefor pay load. In recent years the use of mechanical refrigerating unitsof the compression or absorption type has become almost universal oncargo vessels where one central plant can effectively cool the entirerefrigerated cargo space. However, the application of such mechanicalrefrigeration systems to smaller transportation units, such asrefrigerator cars and refrigerator motor trucks has not been adapted toany great extent. This situation has in part been due to the fact thatsuch mechanical refrigeration systems require the supervision of anengineer or skilled mechanic to ensure the proper and continual 2working, and in part due to the high cost of such equipment.

It is the object of our invention to provide a new and useful processfor the refrigeration of food stuffs.

It isanother object of our invention to provide a simple and eflicientapparatus for the refrigeration of compartments on mobile units such asrailroad cars, motor vehicles and airplanes.

It is a further object of our invention to provide a process andapparatus using liquid air as an expendable refrigerant.

By the term 'iliquid air we include all liquefied mixtures of oxygen andnitrogen. In other words, We contemplate by the term liquid air mixturesconsisting of oxygen and nitrogen in the proportions occurring in natureas well as "liquid air produced as a by-product of industrial processeswherein the proportions of oxygen and nitrogen may vary considerablyfrom the proportions occurring in nature. This liquid air may in fact besubstantially pure oxygen or substantially pure nitrogen.

Another object of our invention is to provide a process and apparatuswhereby the food stuffs being transported are supplied with a continuousstream of cooled air to affect favorably the freshness of the foodstuffs.

The further objects of our invention. will be apparent from thefollowing detailed description of specific embodiments of our invention,and by referring to the accompanying drawings.

Figure I is a longitudinal section of a refrigerator car showing ourrefrigeration system.

Figure II is a sectional plan view of the refrigerator car of Figure Itaken along the line 11-11.

Figure III is an enlarged sectional view of the control valve anddistributor shown in Figures I and II.

Figure IV is an enlarged sectional view of a cylinder relief valve shownin Figures I and II.

Referring to Figures I and II, numeral l represents the outsidesheathing of a railroad refrigerator car.

Located under the floor of the car along each side of the main girder 2are four double walled liquid air cylinders 3 preferably of the dewar orvacuum flask type. These cylinders are provided with baiiies to preventsurging of the contents and are also provided with eduction tubes 4.

The two cylinders on the same side of the girder 3 are connectedtogether by a manifold 5 and are each provided with a shut off valve 6.

The manifolds 5 are each connected to riser pipes I which are verticallymounted inside the insulation of thecar and are joined to each other inthe roof of the car at a T fitting 8.

The third arm of the T fitting is connected to a solenoid type controlvalve 9. The details of this valve 9 and its associated parts may beseen in Figure 111 to which further reference will be made later herein.On the outlet side of the control valve 9 a distribution manifold I9 isattached. Diffusion pans II are positioned under' an open ended pipe IS.The valve member I3 is provided with an elongated stem II which extendsthrough the wall of the pipe IS.

The upper end of the valve stem I1 is threaded and provided with aknurled nut It so that the tension of the valve spring may be overcomeand the valve member lifted when refilling the liquid air cylinder.

A dust cap l9 covers the exterior end of the valve stem and theadjusting nut Id.

The details of construction of the control valve 9 and associatedmechanism can be readily seen by referring to Figure 111.

The control valve 9 comprises a pintle valve member 20 cooperating withan annular seat 2|. A spring 22 surrounding a valve stem 23 connected tothe valve member 20 is employed to keep the valve member normallyagainst the seat 2!. The upper end of the valve stem 23 is attached to ametallic armature 24. This armature 24 is free to move within a coil (orsolenoid) 25 of insulated wire.

A regulating needle-26 is threaded into the wall of the valve body andmay be adjusted so as to partially obstruct the free fiow through theseating member 2! when valve member 20 is raised from its seat. A smallorifice or pressure bleed 3| is provided in the wall of the valve 9.

Electrical leads from the solenoid 25 are attached to an adjustablethermostat unit 2'! and to an electric battery 28. The discharge side ofthe valve 9 is connected to the distribution manifold In which increasesin diameter towards its discharge ends 29. The discharge manifold ispositioned over the diffusion pans II and is supported by suitablehangers from the roof of the car.

The operation of the system is as follows:

Liquid air is charged into the cylinders 3 from an external sourcethrough fill pipes 30 attached to the risers 1. During the fillingoperation it is necessary to vent air displaced by the incoming liquid.This can be done by raising the relief valves l3 from their seats I I bymeans of the adjusting nuts l8.

Upon filling being completed the relief valves are closed.

Due to the evaporation of some of the liquid air internal pressure willbe built up inside the cylinders.

Under this pressure some liquid air will be forced through the eductiontubes into the manifold system and through risers I to the top of thecar. Provided the control valve 9 is open liquid air will pass throughthe valve and through '4 therethrough some of the liquid air will bechanged to the vapor state. The mixed vaporized liquid air andunvaporized liquid air will be eventually discharged to the diffusionpans II where evaporation of the rest of the liquid air will take placeand in so doin will take up heat from the surrounding atmosphere.

The cold vaporized air will flow from the diffusion pans H downwardthrough the interior of the refrigerator car due to its greater densityand in so doing will efiectively reduce the tern-v perature of thecontents of the car.

The thermostatic control unit Ill should be set to the temperaturerequired for the contents of the car and will upon being lowered to thatdesired, act to shut off the flow of current in the solenoid 25. As aconsequence the spring 22 will cause the valve to close and cut off theflow of liquid air to the distribution manifold l9. Upon the temperaturein the refrigeration compartment rising above that desired thethermostat will close an electric circuit so that current flows throughthe solenoid 25 of the valve 9 and will cause the plunger to be drawninto the middle of the solenoid. thus opening the valve and permittingadditional refrigerant to flow into the compartment and therebywithdrawing heat from the contents again lowering the temperature to thedesired figure.

The orifice 3| in the valve 9 permits the continuous passage of a smallamount of liquid air into the distribution manifold ID. This flow ofliquid air prevents the back flow of humidified car atmosphere into themanifold durin periods when the valve member 20 is on its seat 2!. Backflow of humidified car atmosphere would result in water ice forming onthe inside of the manifold which would impair the normal operation ofthe system.

As will be apparent this cycle will be repeated again and again Thefrequency, will; of course. depend upon various factors such as thesensitivity of the thermostat and the efilciency of the insulation ofthe refrigerator car.

The system will operate with only a few pounds pressure existing on thesurface of the liquid air in the cylinders. As it is not practical toobtain perfect insulationv some heat will be transmitted to the liquidair in the cylinders 3 from the atmosphere. The heat absorbed will causeebullition of liquid air in the cylinders and the eventual creation of ahigh internal pressure in the cylinders (provided no means of releasingthis pressure is provided).

In the drawings we have shown a spring loaded pressure release valve l2for this purpose. The operation of this valve is arranged so that uponthe pressure on the surface of the liquid air in the cylinders exceedinga predetermined value. for example, 10 lbs. per square inch, the valvemember l3 will rise from its seat It and vent the excess gas throughpipe It.

In order to avoid the formation of ice on the valve mechanism and toprevent the loss of refrigeration the exterior of each relief valve ispreferably covered with a heavy insulation coating of asbestos, magnesiaor other well known insulating material.

Owing to the introduction of liquid air and vaporized liquid air intothe interior of the refrigerator car, it will be apparent that asuperatmospheric pressure would eventually build up inside the car,providing there were no provision for the relief thereof.

the distribution manifold 10. During its passage In order to relievethis pressure louvre type vents 32 in the end walls of the refrigeratorcar or in the sides can be provided. Where our system is installed in anexisting refrigerator car originally designed for the use of ice,ventilation can also be effected by partially opening one or more of thehatches normally fitted in the roof of such cars. Other conventionalventilator means can of course be provided.

It will be appreciated that we may make specific changes in theapparatus shown. For example, we may use a source of electric currentother than a storage battery and we may in some cases use a controlvalve operated by means other than an electric current such ascompressed air.

It should also be appreciated that we contemplate the possibility ofusing liquid air cylinders of the single wall type heavily insulatedwith asbestos, glass wool or other suitable thermal insulatingsubstance,

We contemplate that the invention can be applied to other mobileequipment such as motor trucks and airplanes. The system disclosed canlikewise be used for stationary refrigeration service such as inhousehold refrigerators, cold storage warehouses, deep freeze lockersand the like and may also be used in air conditioning systems.

We further contemplate that where the ripening of produce has to beheavily retarded that liquid air of substantially pure nitrogen can beused to advantage in the refrigeration system for this purpose and thatvice versa substantially pure oxygen can be used to hasten the ripeningof the produce.

We claim as our invention: I

1. A process for refrigeration using liquid air comprising maintaining asuperatmospheric pressure on the surface of liquid air in an insulatedstorage vessel, admitting liquid air in controlled amounts from saidstorage vessel onto an unconfined diifusion receptacle within theinterior and near the top of a refrigerator compartment, and vaporizingthe admitted liquid freely from said receptacle.

2. A process for refrigeration using liquid air comprising maintaining acontrolled superatmospheric pressure on the surface of liquid air in aninsulated container, flowing liquid air in controlled amounts from saidcontainer onto an unconfined difiusion receptacle within a refrigerationcompartment through a tubular passageway which is in free communicationwith the interior of said compartment, controlling the amount of liquidair so admitted by means of the temperature existing in saidrefrigerator compartment vaporizing the admitted liquid air freely fromsaid receptacle, and continuously flowing a small amount of liquid airthrough said passageway irrespective of said temperature to prevent theback flow of air from said compartment into said passageway.

3. Apparatus for refrigeration using liquid air comprising arefrigerator compartment, a closed insulated container for liquid air, apressure relief valve attached to said container, a control valve,eduction piping extending from the bottom of said insulated container toone side of said control valve, an open diffusion pan within saidrefrigerator compartment, conduit means for conducting liquid air fromsaid control valve onto said pan, and a thermostatic device in saidcomance with the temperature existing in the refrigerator compartment.

4. The apparatus according to claim3 wherein the conduit means is atubular pipe having its discharge end in spaced relation above said panand directed downwardly toward the pan, and having a cross-sectionalarea increasing progressively from said control valve to the saiddischarge end.

5. Apparatus for refrigeration using liquid air comprising arefrigerator compartment, a closed insulated container for liquid air, acontrol valve, piping extending from the bottom of said insulatedcontainer to one side of said control valve, a conduit from the otherside of said control valve to the interior of said refrigeratorcompartment, a thermostat in said compartment connected to said controlvalve whereby said control valve is operated according to thetemperature condition in said compartment and a bleed passagewayconnected in parallel with said control valve for flowing a small amountof liquid air through said conduit on the other side of said controlvalve irrespective of the temperature in said compartment.

6. Apparatus for refrigeration using liquid air comprising arefrigerator compartment, a closed insulated container for liquid air, apressure relief valve attached to said container, a control valve,eduction piping extending from the bottom of said insulated container toone side of said control valve, a distribution conduit from the otherside of said control valve to the interior of said refrigeratorcompartment, open diffusion pans under the discharge ends of saiddistribution conduit and spaced therefrom, the discharge ends of saiddistribution conduit being disposed to discharge liquid air from saidconduit onto said pans and a thermostatic device in said compartmentconnected to said control valve so as to open and close said controlvalve in accordance with the temperature existing in the refrigeratorcompartment.

7. The apparatus according to claim 6 wherein the pans are located nearthe top of said refrigerator compartment.

8. The apparatus according to claim 6 wherein there is provided a bleedpassageway connected in parallel with said control valve for flowing asmall quantity of liquid air through said distribution conduitirrespective of the temperature of said compartment.

9. The apparatus according to claim 6 wherein there is provided a bleedpassageway connected in parallel with said control valve for flowing asmall quantity of liquid air through said tubular pipe irrespective ofthe temperature of said compartment.

ROBERT K. DEUTSCH. FRITHJOF A. LARSON. VERNON E. MIDDLEBROOK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 686,531 Ostergran Nov. 12, 1901927,595 Place July 13, 1909 966,076 Babrick Aug. 2, 1910 2,089,428 Rosset al Aug. 10, 1937 2,247,850 Rayburn July 1, 1941 2,309,938

Diserens et a1. Feb. 2, 1943

